An unusual case of dermatitis herpetiformis.

An adolescent boy whose initial presentation consisted of an asymmetric, nonvesicular rash was eventually diagnosed with dermatitis herpetiformis (DH). Certain factors, including lesions limited to the genitals, an initial biopsy revealing nonspecific findings on microscopy studies, and the absence of characteristic direct immunofluorescence findings lessened initial clinical suspicions of DH over that of scabies infestation. Classic microscopic findings of DH were identified on repeat biopsy. Serologic studies revealed immunoglobulin A (IgA) endomysial and IgA tissue transglutaminase positivity. Response to dapsone proved dramatic. Histopathologic findings, serology, and response to treatment rather than classical clinical findings and direct immunofluorescence supported the diagnosis of DH in this case.